1. Field of the Invention
The present invention relates to a resin composition usable for encapsulating a semiconductor device for the purpose of encapsulating a gap formed between the wiring circuit board and the semiconductor element (hereinafter simply referred to as “resin composition”), and a semiconductor device in which the resin encapsulation is carried out with the resin composition for encapsulating a semiconductor device.
2. Discussion of the Related Art
As the recent requirements accompanied by multi-functionality and miniaturization of a semiconductor device, a flip-chip mounting in which a semiconductor element is mounted on a wiring circuit board with a facedown structure has been carried out. Generally, in the flip-chip mounting, a gap between a semiconductor element and a wiring circuit board is encapsulated with a thermosetting resin composition in order to protect the semiconductor element.
A conventional manufacturing method with the flip-chip mounting comprises the step of creating patterns on a wafer, forming bumps, cutting the wafer into individual semiconductor elements, mounting the semiconductor elements on a wiring circuit board, and carrying out resin encapsulation. On the other hand, in order to improve the productivity of semiconductor devices, there has been desired a method comprising the steps of creating patterns on a wafer, forming bumps, feeding an adhesive (resin composition) to a patterned side, cutting the wafer into individual semiconductor elements, and mounting the semiconductor element on a wiring circuit board in a face-down structure (hereinafter referred to as wafer level flip-chip mounting method) (see, for instance, Japanese Patent Laid-Open No. 2001-144120). In the wafer level flip chip mounting method mentioned above, since a thermosetting resin composition is fed to a patterned side, the wafer is cut into individual semiconductor elements, and the semiconductor elements obtained are mounted in a circuit substrate, it is necessary that the thermosetting resin composition retains a pattern-recognizable transmittance. On the other hand, in the thermosetting resin composition for encapsulating a connecting portion of the flip chip package, generally, thermal expansion coefficient or water absorption is lowered by containing an inorganic filler in an organic resin composition, thereby satisfying thermal cycle test performance and solder resistance of semiconductor devices (for instance, see Japanese Patent Laid-Open No. 2003-138100).
However, in the conventionally usable inorganic fillers, since it has been difficult to control the refractive index to a given value, it has been difficult to retain a pattern-recognizable transmittance by the adjustment of the refractive index in a desired organic resin composition. In addition, if the content of the inorganic filler in the organic resin composition is lowered in order to retain pattern-recognizable transmittance, the thermal expansion coefficient or water absorption of the organic resin composition increases, so that a semiconductor device having sufficient thermal cycle test performance and solder resistance could not be obtained. Further, the thermal conductivity of the organic resin composition is lowered by lowering the content of the inorganic filler, thereby giving arise to such a problem that the heat radiation property of the semiconductor device is lowered.
Accordingly, an object of the present invention is to provide a resin composition for encapsulating a semiconductor device suitably usable for the flip-chip mounting, in which excellent operability is obtained, the resin composition giving excellent electric connection reliability and heat radiation property to the semiconductor device after the resin encapsulation; and a semiconductor device in which resin encapsulation is carried out with the resin composition.
These and other objects of the present invention will be apparent from the following description.